From: Arnd Bergmann <arnd@arndb.de>
To: Andrew Vagin <avagin@parallels.com>
Cc: Andrey Vagin <avagin@openvz.org>, linux-kernel@vger.kernel.org,
        linux-api@vger.kernel.org, Oleg Nesterov <oleg@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Cyrill Gorcunov <gorcunov@openvz.org>,
        Pavel Emelyanov <xemul@parallels.com>, Roger Luethi <rl@hellgate.ch>
Subject: Re: [PATCH 0/7] [RFC] kernel: add a netlink interface to get information about processes
Date: Wed, 18 Feb 2015 12:06:40 +0100
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On Wednesday 18 February 2015 00:33:13 Andrew Vagin wrote:
> On Tue, Feb 17, 2015 at 09:53:09AM +0100, Arnd Bergmann wrote:
> > On Tuesday 17 February 2015 11:20:19 Andrey Vagin wrote:
> > > task_diag is based on netlink sockets and looks like socket-diag, which
> > > is used to get information about sockets.
> > > 
> > > A request is described by the task_diag_pid structure:
> > > 
> > > struct task_diag_pid {
> > >        __u64   show_flags;      /* specify which information are required */
> > >        __u64   dump_stratagy;   /* specify a group of processes */
> > > 
> > >        __u32   pid;
> > > };
> > 
> > Can you explain how the interface relates to the 'taskstats' genetlink
> > API? Did you consider extending that interface to provide the
> > information you need instead of basing on the socket-diag?
> 
> It isn't based on the socket-diag, it looks like socket-diag.
> 
> Current task_diag registers a new genl family, but we can use the taskstats
> family and add task_diag commands to it.

What I meant was more along the lines of making it look like taskstats
by adding new fields to 'struct taskstat' for what you want return.
I don't know if that is possible or a good idea for the information
you want to get out of the kernel, but it seems like a more natural
interface, as it already has some of the same data (comm, gid, pid,
ppid, ...).

	Arnd
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